added MaterialData classes and associated Enums for COAL, CROPS, LOG, LEAVES, STEP, and DOUBLE_STEP

By: sunkid <sunkid@iminurnetz.com>

paper-api/src/main/java/org/bukkit/material/Coal.java

@@ -0,0 +1,44 @@
+package org.bukkit.material;
+
+import org.bukkit.CoalType;
+import org.bukkit.Material;
+
+/**
+ * Represents the different types of coals.
+ * @author sunkid
+ */
+public class Coal extends MaterialData {
+       public Coal(final int type) {
+            super(type);
+        }
+
+        public Coal(final Material type) {
+            super(type);
+        }
+
+        public Coal(final int type, final byte data) {
+            super(type, data);
+        }
+
+        public Coal(final Material type, final byte data) {
+            super(type, data);
+        }
+
+        /**
+         * Gets the current type of this coal
+         *
+         * @return CoalType of this coal
+         */
+        public CoalType getType() {
+            return CoalType.getByData(getData());
+        }
+
+        /**
+         * Sets the type of this coal
+         *
+         * @param type New type of this coal
+         */
+        public void setSpecies(CoalType type) {
+            setData(type.getData());
+        }
+}